The present invention relates to an endoscope apparatus and, more particularly, to an electronic endoscope apparatus having a solid state image sensor arranged in the distal end thereof.
An electronic endoscope apparatus has a solid state image sensor arranged in the distal end portion thereof, so that image signals obtained from the image sensor are displayed on a monitor as an endoscopic image. The endoscopic image is displayed on the right, left, or central portion of the screen of the monitor, and character data concerning a patient under examination, etc. is displayed on the other blank part of the screen.
Preferably, the solid state image sensor of the electronic endoscope apparatus may be constructed such that number nV of its vertical pixels is equal to that of the scanning lines of the standard type TV set (e.g., the NTSC type), and that the horizontal resolution and the vertical resolution are almost equal to each other. However, since the monitor screen is not a perfect rectangle, an image of a smaller area than the area of the image actually picked-up by the image sensor is displayed on the screen. However, since the outline of the endoscopic image and the monitor screen are of different proportions, the endoscopic image cannot be displayed in its entirety on the monitor screen. Thus, there is always some part of the imaging area of the image sensor which is not displayed. In order to eliminate this problem, the solid state image sensor may be designed according to the length-to-width (nV-to-nH) ratio 3 : 4 of the monitor screen such that the endoscopic image covers only the area of the length-to-width ratio nV : nH"(=3/4.times.nH).
However, current semiconductor technology has its limits as regards the miniaturization of pixels of a solid state image sensor. The conventional solid state image sensor described above is not small enough to be able to be fitted in the distal end of the endoscope. As a result, the diameter of the distal end of the endoscope cannot be reduced.